Folic Acid Can Mask Dangerous Vitamin B12 Deficiency, Experts Warn
Folic acid is a crucial supplement in preventive medicine, especially for women before and during early pregnancy, as it reduces the risk of neural tube defects in the fetus. However, uncontrolled intake of high doses of folic acid can mask a serious vitamin B12 deficiency in certain individuals. This masking effect can improve blood test results and reduce anemia symptoms, misleading both patients and doctors, while the underlying B12 deficiency continues to damage the nervous system.
Symptoms of untreated B12 deficiency include numbness in hands and feet, burning sensations, sensory loss, balance problems, weakness, memory issues, confusion, depression, and potentially long-term neurological damage. Groups at risk for B12 deficiency include vegans and vegetarians who do not supplement B12, elderly people, those who have undergone bariatric surgery, patients with intestinal diseases or celiac disease, individuals with atrophic gastritis, long-term metformin users, chronic users of acid-reducing medications, and people with unexplained anemia or neurological symptoms.
For these populations, taking folic acid supplements without prior B12 testing can obscure the diagnosis. Recommended folic acid doses vary: women planning pregnancy or in early pregnancy have specific guidelines, sometimes requiring higher doses under medical supervision, which differ from high-dose folic acid use in older adults for general blood health. Additionally, folic acid is found in fortified foods and multivitamins, so total intake may be higher than expected.
Proper diagnosis involves blood tests including B12 levels, complete blood count, and sometimes methylmalonic acid and homocysteine measurements. If neurological symptoms are present, treatment must go beyond correcting anemia and address the B12 deficiency promptly, often with injections. Delayed treatment reduces the chance of full neurological recovery. Dr. Itay Gal emphasizes that while folic acid is beneficial, it must be used carefully to avoid hiding dangerous deficiencies.
